Comparative evaluation of antioxidant and antimicrobial properties of bioactive peptides from enzymatically hydrolyzed quail slaughterhouse by-products encapsulated in different nanovesicle systems

Bioactive peptides derived from protein-rich quail slaughterhouse by-products have potential antioxidant and antibacterial activities; however, their instability may limit their practical applications. This study compared uncoated nanoliposomes, chitosan-coated nanoliposomes, and nanoniosomes as delivery systems for enzymatically produced quail by-product peptides. The peptides were obtained using an alkaline protease from Bacillus subtilis under the selected hydrolysis conditions of pH 8.0, 37 °C, an enzyme-to-substrate ratio of 1.5%, and 8 h of hydrolysis. The encapsulation efficiency, peptide release under simulated gastric and intestinal conditions, antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3- ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays, as well as antibacterial activity based on minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), were evaluated. All nanovesicle assays were performed in triplicate and analyzed using nonparametric statistical tests at p<0.05. Encapsulation efficiency significantly differed among uncoated nanoliposomes (68.65 ± 0.19%), chitosan-coated nanoliposomes (73.70 ± 0.22%), and nanoniosomes (70.51 ± 0.25%; overall p=0.02), with a significant difference observed only between uncoated and chitosan-coated nanoliposomes (adjusted p=0.007). Chitosan-coated nanoliposomes exhibited lower peptide release than uncoated nanoliposomes under both simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) conditions and showed more favorable mean antioxidant activity values, while their differences from nanoniosomes were not statistically significant. Furthermore, peptide-loaded chitosan-coated nanoliposomes and nanoniosomes exhibited the lowest MIC and MBC values, depending on the bacterial species. Overall, chitosan coating enhanced the encapsulation and controlled-release performance of nanoliposomes compared with uncoated nanoliposomes, while both chitosan-coated nanoliposomes and nanoniosomes demonstrated promising potential as peptide-delivery systems with antioxidant and antibacterial functionality in vitro.